Many people donât realize that chest pain and shortness of breath can be symptoms of RA. In fact, heart and lung problems can be a serious complication of the disease. People with RA have an increased incidence of blocked and hardened arteries, which could lead to heart attack or stroke, especially if they also smoke.
Calcium carbonate spicules of calcareous sponges have been found in Early Cambrian rocks from about 530 to 523 million years ago in Australia. Other probable demosponges have been found in the Early Cambrian Chengjiang fauna, from 525 to 520 million years ago. Freshwater sponges appear to be much younger, as the earliest known fossils date from the Mid-Eocene period about 48 to 40 million years ago.
This is the origin of the Metazoa, or multicellular organisms (Dawkins 2004). An experiment performed by H. V. Wilson of the University of North Carolina was published in the 1907 issue of the Journal of Experimental Zoology (Wilson 1907). He separated the cells of a living sponge by forcing it through a fine sieve.heir skeleton is made of tiny, needle-like splinters, or a mesh of protein called spongin (2) Most of the Demospongiae are made of spongin. Some of the sponges are made of both spicules and spongin. Bath sponges are made of calcereous or siliceous spicules, and they are therefore soft to the touch.